/*************************************************************************
 > File Name: monolith/util/base64.cc
 > Author: dzhang
 > Mail: dong.zhang@ingenic.com
 > Created Time : Wed 03 Feb 2021 09:16:54 PM CST
 > Description:
 ************************************************************************/

#include "monolith/util/base64.h"
#include "monolith/core/macros.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
CC_NAME_SPACE_BEGIN

namespace util {

static unsigned char *base64_table =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static int base64_decodetable[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0,
        0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
        16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27, 28,
        29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
        47, 48, 49, 50, 51 };

unsigned char* base64_encode(unsigned char *str, long str_len) {
    long len;
    unsigned char *res;
    int i, j;
    if (str_len % 3 == 0)
        len = str_len / 3 * 4;
    else
        len = (str_len / 3 + 1) * 4;

    res = malloc(sizeof(unsigned char) * len + 1);
    res[len] = '\0';
    for (i = 0, j = 0; i < len - 2; j += 3, i += 4) {
        res[i] = base64_table[str[j] >> 2]; //取出第一个字符的前6位并找出对应的结果字符
        res[i + 1] = base64_table[(str[j] & 0x3) << 4 | (str[j + 1] >> 4)]; //将第一个字符的后位与第二个字符的前4位进行组合并找到对应的结果字符
        res[i + 2] = base64_table[(str[j + 1] & 0xf) << 2 | (str[j + 2] >> 6)]; //将第二个字符的后4位与第三个字符的前2位组合并找出对应的结果字符
        res[i + 3] = base64_table[str[j + 2] & 0x3f]; //取出第三个字符的后6位并找出结果字符
    }
    switch (str_len % 3) {
    case 1:
        res[i - 2] = '=';
        res[i - 1] = '=';
        break;
    case 2:
        res[i - 1] = '=';
        break;
    }
    return res;
}

unsigned char* base64_decode(unsigned char *code) {
    long len;
    long str_len;
    unsigned char *res;
    int i, j;

    len = strlen((char*) code);
    if (strstr((char*) code, "=="))
        str_len = len / 4 * 3 - 2;
    else if (strstr((char*) code, "="))
        str_len = len / 4 * 3 - 1;
    else
        str_len = len / 4 * 3;

    res = malloc(sizeof(unsigned char) * str_len + 1);
    res[str_len] = '\0';

    for (i = 0, j = 0; i < len - 2; j += 3, i += 4) {
        res[j] = ((unsigned char) base64_decodetable[code[i]]) << 2
                | (((unsigned char) base64_decodetable[code[i + 1]]) >> 4); //取出第一个字符对应base64表的十进制数的前6位与第二个字符对应base64表的十进制数的后2位进行组合
        res[j + 1] = (((unsigned char) base64_decodetable[code[i + 1]]) << 4)
                | (((unsigned char) base64_decodetable[code[i + 2]]) >> 2); //取出第二个字符对应base64表的十进制数的后4位与第三个字符对应bas464表的十进制数的后4位进行组合
        res[j + 2] = (((unsigned char) base64_decodetable[code[i + 2]]) << 6)
                | ((unsigned char) base64_decodetable[code[i + 3]]); //取出第三个字符对应base64表的十进制数的后2位与第4个字符进行组合
    }
    return res;
}

} // namespace util
CC_NAME_SPACE_END
